Questions tagged [human-biology]
This tag is for questions about the general biological features of human beings (as opposed to the biology of non-humans).
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Does every human eye see the same visible spectrum?
It is said that human eye can see light with wavelength approximately between 400nm and 700nm.
Are these upper and lower bounds same for every human? If not, what are the means and standard ...
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Can the mating of a couple with Rhesus positive and negative blood types result in miscarriage?
Can the combination of $+ve$ and $-ve$ blood groups of a couple be a cause of miscarriage in pregnancy?
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What will happen if a foetus is Rh- and the mother is Rh+?
If a mother has Rh-negative blood and her foetus has Rh-positive blood it will result in rhesus incompatibility and lead to erythroblastosis fetalis. What will happen if the reverse occurs, when a ...
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How does the brain instinctively know the math behind Newtonian Physics?
A 10 year old child does not have the intellectual power to accurately calculate the energy required to throw a ball an arbitrary distance. Yet they are able to accurately throw a ball at a ...
user1199
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The genetic and physiological origins of laughter?
This Wikipedia article defines laughter in many terms, such as...
"a visual expression of happiness, or an inward feeling of joy"
and
"a part of human behavior regulated by the brain, helping ...
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Are unilaterally deaf people able to determine where sound comes from?
My question is on people deafened in one ear, but normal hearing in the other.
Time and level differences between the two ears are only part of how the human body can localize the source of the sound....
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Does mixing alcoholic drinks really make you more drunk?
There is plenty of anecdotal evidence ("beer after wine and you'll feel fine, wine after beer will make you feel queer") that mixing alcoholic drink types leads to a stronger effect, but I can't find ...
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What is the effective relatedness of inbreeding?
If a human inbreeds with a relative, how distant does the relative have to be before the homozygosity in the child is no higher than if the mate were randomly chosen from the global population?
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Why are bald heads so "shiny"?
Why do males with baldness have shiny skin on their head, whereas we don't experience such "shiny skin" in other parts of body without hair.
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Like other animals, why humans don't have species & breeds?
Like other animals, why don't humans have species & breeds ?
Even my pet dog is one type of breed, but we (humans) lack breeds & species? What is the main reason?
user10246
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What is the main challenge in creating a chemical male contraceptive?
More than 50 years after hormonal contraception for women was invented, a contraceptive pill for males is still not available. With the obvious major biological differences in mind, why does it appear ...
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Preferred Aspect Ratio for Human Eyes
Our eyes are spherical, our retina is circular, but still our eyes can see more in the horizontal direction than in vertical direction. Why is it so, why is the preferred aspect ratio not square?
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Where does vasoconstriction occur in limbs?
When cold or in shock a person's blood vessels constrict in order to preserve heat or to move blood flow to protect vital organs. I am interested in the mechanism by which this is achieved. Does ...
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Can females be recreated from male DNA?
A chromosomal male is XY and a chromosomal female is XX. Now imagine if, one day, this world has only males - is it possible to "recreate" a female by using two X chromosomes from two different males?
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How to identify the age of a "living" person?
An Indian old man claims he is [180 years old] now.
We are not able to tell he is 180 or 181 probably. But can we tell he is 90, 120, 100 or 150?
Different people may age differently.
A 60-year ...
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What's the worst that can happen from too much sleep deprivation? Can you die?
It is well known that sleep deprivation causes considerable discomfort in humans (and has even used as a form of torture), but nevertheless there have been people who went through protracted sleep ...
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How are bones growing, if bones are not connected to the brain?
If the bones are not connected to the brain, how is their growth controlled?
This question is not a duplicate of the question Mechanisms of bone growth, as this question deals with how bone growth is ...
user10246
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Is there a biological basis to physical attraction?
Is there something encoded within us that makes us attracted to, e.g., someone
taller or shorter
with blonde or brunette hair
with green or blue eyes?
Or, is this phenomenon completely based on ...
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What influences the timing of human bowel movements in the morning?
I'm trying to understand if the timing of human bowel movements in the morning is associated with the circadian rhythm, and can thus be used to make predictions about the circadian rhythm.
What ...
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Do breasts size depend solely on fat amounts?
I've read the first answer here on quora and it suggests that (not during pregnancy and breastfeeding) breasts differ in size only due to the amount of fats. However, there can be firm or soft breasts ...
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Why don't we build up an immunity to sore throat?
We often get sore throats once or twice a year, and it clears in a few days sometimes without any antibiotics. I was wondering why doesn't our body become immune after clearing a sore throat?
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What is the optimum length of abstinence for maximum ejaculation volume in humans?
There have been papers discussing this, and whether the abstinence period should be 1 week, 2 weeks or other [1, 2]. Some think the time to maximum ejaculation volume is even longer than this.
doi: ...
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Can people with paralyzed eye muscles see?
As far as I am aware, the saccades of the eye are central to visual perception. If the eye is held still, the human stops seeing, even if light is reaching the retina and the visual pathway is intact. ...
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Why do men have a higher hematocrit (red blood cell count) than women?
The hematocrit, also known as packed cell volume (PCV) or erythrocyte volume fraction (EVF), is the volume percentage (%) of red blood cells in blood. It is normally 45% for men and 40% for women.
so,...
user12874
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How Circumcision could reduce the chance for a HIV infection?
Circumcision removes the foreskin of the penis which mainly acts as a cover to the penis. Normally removing the foreskin makes more vulnerable to any STD, so how could circumcision reduce the risk of ...
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Do hormone drugs affect whether a person feels sexual attraction to males or females?
I know that ingesting testosterone and other hormonal drugs may stimulate libido and increase sexual desire.
But I wonder, if a man ingests female hormones such as estrogen, will he experience sexual ...
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Possible to Gain More Weight than the Food You Eat
I was wondering if it's possible to gain more weight than the mass of the food you eat. At a first look, this is impossible because of the principle of mass conservation, but are there other things to ...
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How quickly can the human heart rate rise and fall?
How quickly can the human heart rate rise and lower?
For example lets say a human heart rate is rested and is at 60BPM and that person is suddenly scared to trigger their fight or flight reaction. ...
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Which shades/hues of color are easiest to distinguish for humans?
I'm trying to represent data graphically and am using a variation of hue/lightness to distinguish one data point from the next. I would like to use a color that would allow me to convey most ...
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Adipocyte Density
People who are overweight and wish to lose weight, often do so because they are concerned about looking too big. Their increased size is attributed to an increased volume of fat.
When people try to ...
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Why do people feel pleasure when using roller coasters / centrifuges?
The feeling when using an amusement park unit is usually a pleasure. Why is it not a pain instead?
Are there advantages, from an evolutionary point of view, in loving this potentially dangerous ...
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Why does yawning impair hearing?
When I yawn I can't hear anything happening around me. I also feel some kind of muscles inside my head contract and hear a faint hum, but it is not loud enough to explain not hearing other sounds. I ...
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Why did women historically have such a high mortality rate during birth?
Historically women had a relatively high chance of dying while giving birth.
At first thought it seems to me that this would be a disadvantage for the species for the obvious reason that a dead ...
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Why does plucking nose hair cause tears in the eyes?
It's not a particularly sad or painful thing to pluck a few nose hairs, but it's common for the tear ducts to wet up when doing this.
I would like to know the physiological reason for the ...
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What causes knuckle "popping" and the feeling of relief that comes from it?
Many people like cracking their knuckles. I have always been curious about it.
What happens when we crack knuckles?
What creates the POP sound?
Why do we get a relief-like feeling after doing it?
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Human sleep cycles and dream times, what influences the timing and intensity? Sleep history included
I'm doing sleep and dreams research and have developed an iPhone application to help me track my bedtime, rise time, sleep onset and also mark dreams. The app also monitors overall activity overnight ...
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Effects of Polyphasic vs Monophasic sleep in humans
Why do humans practice monophasic sleep cycles?
When altering one's circadian rhythm to a Polyphasic sleep schedule, how much would that affect development?
Is Monophasic sleep (once per day) ...
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What happens to the food you accidentally aspire?
I'm well aware of the health effects of aspirating solid food and liquids, but I'm interested in the reaction of the body on the biological level to the strange body on our lungs.
After I almost ...
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A timeline of the odds for survival for fertilized eggs and fetuses
I'm looking for data to build a timeline of the odds for survival of a fertilized egg, i.e.,
What are the odds it'll last a week?
What are the odds it'll last a month?
2 months?
(and so on until)...
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Is there a relationship between efficiency of cellular metabolism and warm-blooded-ness?
My BIO 101 book states that when human cells convert glucose to ATP, the process is only approx 35% efficient, and much of the potential energy is lost as heat. However, that heat is useful to us in ...
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Which human body hormonal systems exhibit 24 hour diurnal cyclical activity?
I'm researching the possible connection between the dream content and the activity of various organ or hormonal systems within the human body. I'm looking for information on biological cycles within ...
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Why do sneezes come in pairs or more?
I very rarely sneeze just once, usually there's two coming in a row, and I've noticed the same thing in other people and even in animals. Is there any reason for this?
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How does the body measure dehydration?
What, physically, does the body do to measure it? I assume it's measured by how how turgid or plasmolysed certain 'sample cells' are, or water concentration in the blood,
What is the way they use to ...
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Do blood glucose "spikes" contribute to insulin resistance, or is prolonged elevation required?
There's increasing public discussion about the health risks of chronic insulin resistance* (IR). In many cases there's a focus on high glycemic index foods that "spike" your blood sugar, which implies ...
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What causes Paresthesia (Pins and Needles) at a cellular level?
I've looked it up in plenty of places like the Wikipedia page and such, and it is clear that the most common cause of Paresthesia is either a fair amount of pressure on a specific patch of skin ...
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Why babies cry after they are born?
Well I have noticed that almost all of the babies cry after birth, but some of them (1 to 1,000,000? births) don't cry. So, we have:
Why is this happening (the cry after birth)?
Also why animals ...
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The village of Twins — Mystery behind and Scope
With the presence of more than 200 twins, Kodinhi , a village situated in Malappuram District in Kerala , India , is popularly known as the "Village of Twins".This phenomenon of large ...
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What Would Happen To a Human Who Died In Space And Stayed There For a Prolonged Period of Time? [closed]
Last night I was watching a documentary regarding the Apollo space program, and it spoke about how Apollo 8 orbited the moon 10 times then came back to Earth. It said that while the ship was in orbit ...
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Do biological facts determine when a human fetus is considered alive and human?
I often hear or read this statement:
"It's not a human, it's a fetus."
In other words, some think a fetus is non-human until a certain point.
And another similar statement:
"The fetus isn't ...
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How long human can survive with just drinking water everyday
Can humans live without eating food, just by drinking water? How long can we survive just by drinking water everyday?
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